<!-- 想法：点击信封+信纸(内嵌信纸) -->
<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>信封</title>
    <style>
        body {
            background: #323641;
        }
        
        .letter-image {
            position: absolute;
            top: 50%;
            left: 50%;
            width: 200px;
            height: 200px;
            -webkit-transform: translate(-50%, -50%);
            -moz-transform: translate(-50%, -50%);
            transform: translate(-50%, -50%);
            cursor: pointer;
        }
        
        .animated-mail {
            position: absolute;
            height: 150px;
            width: 200px;
            -webkit-transition: .4s;
            -moz-transition: .4s;
            transition: .4s;
            .body {
                position: absolute;
                bottom: 0;
                width: 0;
                height: 0;
                border-style: solid;
                border-width: 0 0 100px 200px;
                border-color: transparent transparent #e95f55 transparent;
                z-index: 2;
            }
            .top-fold {
                position: absolute;
                top: 50px;
                width: 0;
                height: 0;
                border-style: solid;
                border-width: 50px 100px 0 100px;
                -webkit-transform-origin: 50% 0%;
                -webkit-transition: transform .4s .4s, z-index .2s .4s;
                -moz-transform-origin: 50% 0%;
                -moz-transition: transform .4s .4s, z-index .2s .4s;
                transform-origin: 50% 0%;
                transition: transform .4s .4s, z-index .2s .4s;
                border-color: #cf4a43 transparent transparent transparent;
                z-index: 2;
            }
            .back-fold {
                position: absolute;
                bottom: 0;
                width: 200px;
                height: 100px;
                background: #cf4a43;
                z-index: 0;
            }
            .left-fold {
                position: absolute;
                bottom: 0;
                width: 0;
                height: 0;
                border-style: solid;
                border-width: 50px 0 50px 100px;
                border-color: transparent transparent transparent #e15349;
                z-index: 2;
            }
            .letter {
                left: 20px;
                bottom: 0px;
                position: absolute;
                width: 160px;
                height: 60px;
                background: white;
                z-index: 1;
                overflow: hidden;
                -webkit-transition: .4s .2s;
                -moz-transition: .4s .2s;
                transition: .4s .2s;
                .letter-border {
                    height: 10px;
                    width: 100%;
                    background: repeating-linear-gradient( -45deg, #cb5a5e, #cb5a5e 8px, transparent 8px, transparent 18px);
                }
                .letter-title {
                    margin-top: 10px;
                    margin-left: 5px;
                    height: 10px;
                    width: 40%;
                    background: #cb5a5e;
                }
                .letter-context {
                    margin-top: 10px;
                    margin-left: 5px;
                    height: 10px;
                    width: 20%;
                    background: #cb5a5e;
                }
                .letter-stamp {
                    margin-top: 30px;
                    margin-left: 120px;
                    border-radius: 100%;
                    height: 30px;
                    width: 30px;
                    background: #cb5a5e;
                    opacity: 0.3;
                }
            }
        }
        
        .shadow {
            position: absolute;
            top: 200px;
            left: 50%;
            width: 400px;
            height: 30px;
            transition: .4s;
            transform: translateX(-50%);
            -webkit-transition: .4s;
            -webkit-transform: translateX(-50%);
            -moz-transition: .4s;
            -moz-transform: translateX(-50%);
            border-radius: 100%;
            background: radial-gradient(rgba(0, 0, 0, 0.5), rgba(0, 0, 0, 0.0), rgba(0, 0, 0, 0.0));
        }
        
        .letter-image:hover {
            .animated-mail {
                transform: translateY(50px);
                -webkit-transform: translateY(50px);
                -moz-transform: translateY(50px);
            }
            .animated-mail .top-fold {
                transition: transform .4s, z-index .2s;
                transform: rotateX(180deg);
                -webkit-transition: transform .4s, z-index .2s;
                -webkit-transform: rotateX(180deg);
                -moz-transition: transform .4s, z-index .2s;
                -moz-transform: rotateX(180deg);
                z-index: 0;
            }
            .animated-mail .letter {
                height: 180px;
            }
            .shadow {
                width: 250px;
            }
        }
    </style>
</head>

<body>
    <div class="letter-image">
        <div class="animated-mail">
            <div class="back-fold"></div>
            <div class="letter">
                <div class="letter-border"></div>
                <div class="letter-title"></div>
                <div class="letter-context"></div>
                <div class="letter-stamp">
                    <div class="letter-stamp-inner"></div>
                </div>
            </div>
            <div class="top-fold"></div>
            <div class="body"></div>
            <div class="left-fold"></div>
        </div>
        <div class="shadow"></div>
    </div>
</body>

</html>